Electro-magnetic heater



Feb. 10, 1959 J. P. coLLoPY 2,873,343

ELECTRO-MAGNETIC HEATER Filed June 4. 1957 ill I Lm" @Ill f@*Inlyuggaflgwewww 'usm M ll l I INV ENTOR.

United States Patent O ELECTRO-MAGNETIC HEATER Joseph P. Collopy,Phoenix, Ariz., Electro-Soil Company, Phoenix, Delaware assignor toCollopy Ariz., a corporation of The present invention is directed to animproved portable electric heater for providing localized heat tomachinery and the like.

In brief, the improved heater of this invention constitutes anelectrical utility heater combining certain principles of the familiarelectro-magnetic and resistance-type heaters. Heaters of this class aredesigned particularly to heat selected areas of machinery for suchpurposes as heating lubricants and the like to facilitate easy startingand operation.

The prior art has demonstrated two general classes of electricalheaters, a magnetic-type of heater and a resistance-type of heater. Themagnetic heater employs an electro-magnetic coil and core designed topass magnetic ux through the object to be heated and to which the heatermagnetically adheres; the flow of magnetic flux serving to heat suchobject, as for example, the housing of a transmission or the like. Theheating operation of such an electro-magnetic heater is dependent by andlarge on the density and ow of the magnetic ilux and various means areemployed to keep the electro-magnetic coil cool so that the highlyconductive wires thereof will not over heat and destroy themselves.Because of the energy requirements involved in this class of heaters,the same are generally large and cumbersome.

The resistance-type heater does no-t induce heat directly in the metalto lbe heated as does the electro-magnetic type, but produces heat bypassing electrical energy through a high resistance coil which radiatesheat to the item to be heated.

The heater `of my present invention is directed to improvements in thetwo above-named heater types in that certain' features of both vtypesare embodied therein. Briefly, I employ a steel or magnetic core memberwhich is wound with a heater coil of insulated wire in a manner somewhatsimilar to a transformer. The resistance wire is supplied by an ordinary110 volt A. C. source, and the current passing through the resistancecoil produces sufficient magnetic flux in the steel core to hold theheater tightly to a magnetic object to be heated. The resistancewindings also produce sufficient resistance heating to conductively heatthe magnetic core piece and radiate heat to the object to be heated in amanner similar to a conventional resistance heater. By thus combiningthe desirable features of the magnetic and resistance heaters presentlyknown, I am able to economize in the construction of my heater unit andreduce the size and cumbersome characteristics of the normal magneticheater by selecting a resistance coil wire of a desirable characteristicsuficient to obtain proper magnetic pull in the core member, as well asthe desired amount of resistance heating.

The main object of this invention is to produce a new and improvedportable electrically energized heater which heats inductively,conductively, and radiantly.

Another object of this invention is to provide an improvedelectro-magnetic heater in which a magnetic core piece of ferrousmaterial, for instance, is wound with a resistance coil, so that whilethe core piece is magnetized sufliciently to hold the heater to amagnetic object to be heated, the resistance of core winding also heatssuch object.

Still another object of my invention is to provide a new and improvedportable heater especially adapted for localized heating of metalobjects; the same heating by the ow of magnetic flux through the objectand by conduction and radiation from a resistance coil.

The above and further objects, features, and advantages of thisinvention will appear to those familiar in the art from the followingdetailed description and specilications of a first preferred andmodified embodiment thereof shown in the accompanying drawings.

In the drawings:

Figure l is a View in side elevation of my new heater assembly withportions of the heater housing and coil Ibroken away in section toillustrate the features of construction and assembly of the improvedheater of my invention.

Figure 2 is a cross-sectional View taken substantially at line 2 2 ofFigure l and looking in the direction of the arrows thereon; and

Figure 3 is a partial enlarged cross-sectional view of a modified coreconstruction for use with the heater assembly set forth in Figure l.

Turning now to the features of the improved heater of this invention,indicated generally by numeral 1@ in Figure l, it will be recognizedthat the same includes an outer inverted cup-like housing 11 which issubstantially U- shaped in cross section, as best seen in Figure 2, andincludes a top wall l2, two end walls 13, 13, and two side walls 14, 14all integrally related. rl`he housing 11 is open at its bottom side andincludes a manually engageable handle 15 located centrally of its topwall 12. An electrical conductor 16 enters through housing 12substantially at the junction of one end wall 13 and the top wall 12, asbest shown in Figure l. Conductor 16 is preferably insulated from thehousing 11 as by a rubber ferrule 17 or a similar means. The walls ofhousing 11 are preferably covered on their inner faces by a suitableinsulating material such as asbestos, indicated generally at 18.

Mounted within housing 12 and extending substantially longitudinallythereof is a solid'metal core 2t) of iron, steel, or like magneticmaterial. Core 2@ is preferably cast to avoid the expense of a laminatedconstruction. Four holding bolts 21, 21 extend through end walls 13, 13of the cover 11 and thread into arm portions 22, 22 of the core member2t) to hold the latter in position. The core member Ztl, as best shownin Figure l, is substantially C-shaped in side elevation and includes inaddition to the arm portions 22, 22 an innerconnecting body portion 23.The arms 22, 22 of the core member Zt) lie substantially transverse tothe main body portion 23 thereof so as to formulate the C-shaped corepiece arranged with the arm members portions 22, 22 depending from thebody portion 23 (see Figure l).

Mounted about the body portion 23 of the core member 2l) is a winding ofresistance wire, indicated generally by numeral The resistance winding25 is selected suitably such that the core member 20 is heated andmagnetic flux set up therewithin by the electrical energization of thewindings. Ordinarily, the supply cable 16 will lead from a source of ll@volt, 60 cycle A. C., although other vaiues of alternating currentsupply may be employed, the windings 25 being selected accordingly. lnany event, as shown in the drawings, the resistance winding 2S is formedin a series of pancake units 26, 26 separated by air spaces 27, asdesired. It will be noted that the resistance wire 28 of each pancakemeans 26 is insulated suitably and wound in spiral about the body'portion 23 of the core member.

Metal discs 29, 29 are employed to conduct heat from the resistancewire; there being one such disc at each end of the pancake units 26.Several such pancake units 26 are mounted along the length of the corebody portion 23 until the space providedby the design of the core memberis fully employed, as desired. The spiral windings of each pancake unitmay be connected in series, in series-parallel, or in parallel to suitthe voltage most convenient and the amount of heat desired'. A metalbase plate 30 is employed preferably beneath the body of the core member20 in contacting engagement with the several metal heat conductor discs29, 29 for the purpose of transferring the heat generated by theresistance windings to the surface of an object to be heated, asindicated, for example, by line 31 of Figure l.

It will be appreciated, of course, that energization of the windings 25serves to set up magnetic flux in thesolid metal core member 20 which,in turn, causes magnetic attraction between the lower ends of the corearm portions 22, 22 and the magnetic material to be heated, such as atransmission or differential housing. Normal eddy current and hysteresislosses, which are usually avoided in the conventional electro-magneticheater are encouraged in the present device, since such heat losses aretransferred t-o the object to be heated and thus increase the eiciencyof my improved heater.

With reference to Figure 3 of the drawings, I have therein shown amodified form of core winding, indicated generally by numeral 40. Thegeneral assembly of a heater embodying this modified core winding is asabove described, except for the resistance winding 40 which, as shown inFigure 3, is wound in the form of a helix having concentric layersparalleling the body portion 23 of the core member 20. In this form ofcoil, part of the heat from the resistance winding is carried to a space41 (see Figure l) within housing 11 and to the base plate 30 by seriesof'annular metal members of substantially U-shaped cross section,indicated by numeral 42, 42 in Figure 3. Such members 42 serve toseparate adjacent layers of wire 43 which constitutes the winding 40 andalso include arm portions 44 which contact plate 30 to transmit heatthereto. Members 42, 42 are preferably of a material. capable ofconducting heat at a high rate, such as aluminum, and suitable airspaces may be included between members 42 to assist in the transfer ofheat, as desired.

In both forms of the device illustrated in the drawings, the currentflow in the windings produces an alternating magnetic ux in the coremember 20 and the metal being heated. In this manner, part of theheating takes place directly in the object being heated through theinductive pulsation of the magnetic flux therein. The winding alsoproduces magnetic pull between the heater and the object being heated toinsure good contact with the core arms 22, 22. The resistance coil alsoconducts heat through the core piece and radiates heat to the object.

4 From the foregoing, it is believed that those familiar with the artwill recognize the virtues, features, and novel aspects of the improvedheater of my invention, andgwill particularly appreciate the combinedadvantages gained by utilizing a resistance heating coil as the coilwinding of an electro-magnet whereby the desirable magnetic andresistance heating effects previously known individually are nowobtainable in a single device according to my invention. It is furtherto be recognized that while I have herein shown and described thefeatures of my invention as it appears in association with a preferredand moditied form thereof shown in the accompanying drawings, numerouschanges, modifications, and substitutions of equivalents may be madetherein without necessarily departing from the spirit and scope of myinvention. As a consequence, it is not my intention to be limited to theparticulars of the device herein shown and described eX- cept as mayappear in the following appended claims.

I claim:

l. A heater for applying localized heat to an object of magneticmaterial, comprising, a magnetic metal core member having spacedextending arm portions adapted to contact the object to be heated, acoil of electrically conductive wire surrounding said core member forinducing electro-magnetic 'flux therein whereby the heater may bemagnetically attracted and secured to said object, said coil comprisingan electrical resistance heater, and thermal conductor means extendingsubstantially between the coil and said object to conduct heat generatedby said coil to said object.

2. A heater for application to the housing of a transmission or thelike, comprising, an electro-'magnetic coil comprising plural adjacentpancake coil elements connected in series circuit relation, a coremember of magnetic material surrounded by said coil whereby the same ismagnetized by energizing said coil, extending arm portions on said corefor engaging the housing to be heated, said coil constituting anelectric resistance heater, and means for conducting heat generated bysaid coil to the object to be heated comprising metal disc elementsextending substantially between said pancake coil elements and theobject to be heated.

References Cited in the file of this patent UNITED STATES PATENTS457,561 Kennedy Aug. 11, 1891 1,322,416 Fossati Nov. 1S, 1919 1,996,502Brown Apr. 2, 1935 2,010,622 Brown Aug. 6, 1935 2,430,285 Ferris Nov. 4,1947 2,804,535 Tuttle Aug. 27, 1957 FOREIGN PATENTS` 311,121 Italy Sept.21, 1933

